Answer:
z^2 +7z -8 = 0
Step-by-step explanation:
Let z = 3x+2. Then we can substitute z wherever we see 3x+2.
z^2 +7z -8 = 0 . . . . equivalent quadratic
__
This is easily factored to ...
(z -1)(z +8) = 0
So, the original quadratic has solutions ...
(3x +2) -1 = 0
x = -1/3
and
(3x +2) +8 = 0
x = -10/3